The present technique relates generally to the formation of antennae or other conductive structures inside a solid medium. More specifically, the present technique relates to the formation of a conductive antenna within a layered structure, such as a decorative surface covering or laminate.
In the field of asset tracking and inventory, various technologies have emerged which improve both the accuracy and speed by which inventories are tracked relative to fully manual techniques. For example, bar code readers may be used to optically read a bar code label on an asset, allowing that label, and presumably the asset, to be identified automatically by reference to a database which associates bar codes with assets. Information about the product, such as price, may then be returned and other information, such as an inventory count, may be updated.
Such systems have limitations, however. For example, such a scanning process requires a time-consuming sequential scanning process, either by hand or by an automated feeder, which allows only one label to be read at a time. Bar code reading also requires an unobstructed line of sight and a specific orientation of the label to the reader in order for the read to be successful. Because of their optic nature, bar codes are poorly suited for harsh environments, such as wet, dirty, oily, or other harsh environments, which might obscure or damage the bar code label. In addition, bar codes provide only a limited amount of information, usually limited to asset identification. Finally, bar code labels are relatively easy to counterfeit using readily available labels and the printing technology available on a personal computer.
Because of these various limitations or hazards associated with bar code technology and techniques, radio frequency identification (RFID) tags or transponders are attracting interest for use in asset identification and tracking. The RFID system uses radio waves, rather than optical signals, to transfer information from the asset to a reader. The RFID tag typically includes an antenna and a radio communication integrated circuit (IC), or chip. The chip contains electronic memory circuitry which may be read via low wattage radio waves by a remote reader, also known as an interrogator. The tag may also be written to by a remote writer. Because the chip may be written to as well as read, it may be updated with new or additional information throughout the asset lifecycle, such as from manufacture to point of sale.
The RFID system provides several advantages, including being able to read multiple tags simultaneously, including obstructed tags or tags which are otherwise outside the line of sight. Likewise, tags are less likely to be damaged than labels and are significantly more difficult to counterfeit. In addition, RFID tags can be read without human intervention and the delays associated with such intervention. The lack of human intervention is of particular value in applications such as asset tracking where it may be desirable to register the movement or absence of an asset without having an employee manually scan the asset. For example, RFID tags may be utilized for automated inventory tracking, such as in a store, at a warehouse or storage site, or during shipping. In such an embodiment, RFID tags may be associated with each good or asset to be tracked, and antennas strategically placed in the environment may allow one or more readers to, continuously or periodically, determine which tags are present and where they are located relative to the antenna.
While this technique may be useful in some contexts, it also presents a variety of problems. For example, placement of a copper or other metallic antenna structure, such as on a shelf, may disrupt the smoothness of a surface and be aesthetically displeasing. In addition, such exposed placement may make the antenna susceptible to damage from the placement or movement of objects on the shelf. In addition, in a retail or commercial setting, customers or staff may tamper with or damage the exposed antenna.
Furthermore, an antenna may retrieve the RFID tag information from other nearby tags, such as on other shelves or aisles. In such an instance an RFID tag may be read or registered multiple times by different antennas, making it difficult to determine the location of the tag. A technique for incorporating an RFID antenna into a decorative or functional surface or shelf and for isolating an RFID antenna from spurious signals is therefore desirable.